CEEGS Concept


First stage is to demonstrate the feasibility of the concept, solving the main challenge of the interface between the surface/subsurface parts, currently in TRL2. The rest of the components have higher TRLs. The project will set the interface and global concept into TRL 4. A 20 kW lab demonstration for the interface, TRL4, shall focus on the CO2 cycle and its operability. It will take three years. If successful, a second stage would build a demonstrator of 100 kW that integrates subsurface and surface components to reach a TRL6 in a second, 3-year project. A third stage 3-year project would impulse the technology up to a commercial scale.


It is a scalable system with the potential for high-performance, high-capacity energy storage. It can be used for electricity storage and production, heating and cooling, also providing partial CO2 sequestration. The concept minimises costs and surface impact, increases the energy storage capacity, and delivers energy in different forms, providing high versatility due to integration possibilities in multiple applications.


A novel concept integrating thermoelectric energy storage based on reversible transcritical CO2 cycles, for renewable energy, both in the form of electricity, thermal, and CO2 storage in geological formations.


Development of a proof of concept, Technology Readiness Level 4, based on the integration of models for system, components and energy system integration, a lab demonstration on a 20 kW power scale, as well as experimental data focusing on the challenges for the interface between surface components and underground systems, where there is the knowledge and technological gap.


A multidisciplinary consortium with expertise in energy (turbomachinery, processes, heat exchange, energy storage, thermal systems, etc.), geology (well designs, CO2 underground storage, etc.), and social sciences (risk perception, public engagement) with the support of leading European geology associations and industries in the energy sectors.